Blowout preventer guide assembly for off-shore drilling vessel

ABSTRACT

Apparatus for guiding a blowout preventor stack assembly through the moon pool or drilling well of a drilling ship or semisubmersible platform. Guide means rigidly secured to the vessel form a pair of spaced parallel tracks extending vertically along one side of the moon pool from a point above the deck down to or into the water. The blowout preventor assembly includes guide elements which engage with the track when the assembly is moved into position over the moon pool. The stack assembly is then lowered down the guide means into the water below the vessel.

United States Patent 1191 Hooper Sept. 2, 1975 BLOWOUT PREVENTER GUIDE3,817,412 6/1974 Mercieret al. 114 .5 D

$223411! FOR OFF-SHORE DRILLING OTHER PUBLICATIONS SEDCO 702-First ofthe New Series, Donald M. Tay- [75] Inventor: galvifd William Hooper, LaHabra, Ocean Int/Mm, May 973 29 [73] Assignee: Global Marine Inc., LosAngeles, Primary Examiner F Abbott C lif Assistant ExaminerRichard E. Favreau Art ,A t, F Ch't',Pk &H1 [22] Filed: Mar- 12, 1974 orney gen 0rzrm rls 1e ar er ae [21] Appl. No.: 450,362 [57] ABSTRACT Apparatus forguiding a blowout preventor stack as- [52] US. Cl. 166/.5; 175/5; 114/.5D sembly through the moon pool or drilling well of a [51] Int. Cl. E21B7/12 drilling ship or semisubmersible platform. Guide [58] Field ofSearch l66/.5, .6; 175/5, 7, 10; means rigidly secured to the vesselform a pair of 114/.5 D spaced parallel tracks extending verticallyalong one side of the moon pool from a point above the deck [56]References Cited down to or into the water. The blowout preventor as-UNlTED S S PATENTS sembly includes guide elements which engage with the3,189,093 6/1965 DeVries 166/.5 track when the assembly moved l" posmoOver 3 226 72s 12/1965 Walvoord 166/.5 the The Stack assembly lwered3:333:562 8/1967 Deal et aL 114/5 D down the guide means into the waterbelow the vessel.

3,498,392 3/l970 Knorr 175/5 3,739,736 6 1973 Carreau et al. 114/.5 D 10w -1 Drawmg F'gures I /fi We x4 H2 =zn y PATENTEU 2|975 3,902,554

sum 1 0r 7 PATENTED 2|975 3.902 554 SHEET 2 [1f PATENTED 2|975 3 902,554

SHEET u pg 1 BLOWOUT PREVENTER GUIDE ASSEMBLY FOR OFF-SHORE DRILLINGVESSEL FIELD OF THE INVENTION This invention relates to off-shoredrilling vessels, and more particularly, is concerned with means forguiding a blowout preventor stack from the deck of the vessel to themoon pool into the water.

BACKGROUND OF THE INVENTION The use of drilling vessels andsemisubmersible platforms which buoyantly support a drilling rig over asubsurface drill site are well known. Conventional practice involvesfirst positioning a base or template which is anchored to the sea floorover the drill site. A blowout preventer stack is then mounted on theplatform and connected to the top of the surface casing. A riser extendsfrom the top of the blowout preventer stack to the surface through whichthe drill stern can be lowered into the hole and through which thedrilling mud is circulated back to the surface.

As deeper wells with their higher pressures are drilled, larger blowoutpreventer stacks have been required. Such a stack, for example, may havea bore of over 20 inches, and may stand as high as 40 ft. in height andweigh up to 200 tons. Because of its large size and weight, themaneuvering of the blowout preventer stack from the deck down throughthe moon pool or drilling well by lowering it on the end of the riserdown to the sea floor presents a considerable problem, particularly on aheaving, rolling vessel. The heavy mass of the blowout preventer stacksuspended on the lower end of the riser tends to swing from side to sidein response to motions of the floating vessel. Obviously if such heavyequipment were to swing against the sides of the moon pool or othersurrounding structure or equipment, severe damage could easily result.

It is therefore desirable to provide some arrangement for rigidlyconstraining the blowout preventer stack while it is being moved intoposition over the moon pool and lowered into the water beneath thevessel. Once lowered into the water, the damping effect of the waterprevents any tendency of the stack to swing back and forth with motionof the vessel, and the blowout preventer stack can be easily constrainedby the conventional guide lines which extend between the vessel and thetemplate.

One arrangement for handling the lowering of a blowout preventer stackis described in the article SEDCO 702 First of the New Series in the May1973 issue of Ocean Industry, page 29. In this arrangement, the blowoutpreventer stack is initially stored on a test stump. A bridge crane isused to lift the stack off the stump. A special jig is used to rigidlysecure the blowout preventer stack to the bridge frame. The bridge cranemoves the stack over the drill hole. The stack is then lowered ontospider beams, the guide lines are attached and the riser pipe is stabbedinto the top of the stack. The stack is lifted off the spider beams bymeans of the riser and drilling rig, the spider beams are spread apartand the stack is lowered into the water. The stack is constrained byguides on either side of the stack which constrain the stack while it islowered into the water.

SUMMARY OF THE INVENTION Applicants invention is directed to a methodand apparatus for transferring the blowout preventer stack from its teststump onto the end of the riser for lowering the stack through the drillopening into the water. This is accomplished without the need of abridge crane and a lift frame or jig torestrain the stack while it isbeing lifted and moved by the bridge crane. Applicants arrangement alsoavoids the necessity of lowering the stack onto the vertical guides.

BRIEF DESCRIPTION OF THE DRAWINGS For a better understanding of theinvention reference should be made to the accompanying drawings,wherein:

FIG. 1 is an elevational view of a first embodiment of the presentinvention;

FIG. 2 is a plan view of the embodiment of FIG. 1;

FIG. 3 is a schematic perspective view of the embodiment of FIG. 1;

FIGS. 4, 5, and 6 show details of the track and associated mountingstructure;

FIG. 7 is a side elevational view of the coupling unit;

FIG. 8 is a top view of the coupling unit;

FIG. 9 is a plan view of an alternative embodiment of the presentinvention;

FIG. 10 is a front elevational view of the second embodiment;

FIG. 11 is a side elevational view of the second embodiment of theinvention; and

FIGS. 12, 13, and 14 show constructional details of the secondembodiment.

Detailed Description Referring to the embodiment of FIGS. 1 through 8,there is shown a portion of a drilling ship in section, the shipincluding a main deck 10 and a bottom 12. A drilling opening or moonpool 1.4 extends vertically be tween the deck 10 and bottom 12 and isopen to the sea, water rising in the moon pool to the indicated waterlevel W/ L. A drilling rig (not shown) is supported over the moon pool14 by box girders 16 supported at their ends from the deck 1(ll bysuperstructure (not shown), the box girders 16 spanning the space abovethe moon pool 14.

Drilling ships for carrying out subsurface drilling for oil are wellknown. The ship is located over the drill site and anchored. A base ortemplate is then anchored to the ocean floor and a casing is set whichterminates at the template. Before deep drilling is commenced, a blowoutpreventer stack is then mounted on the template and secured to the topof the casing. A riser is attached to the top of the stack and extendsup into the moon pool 14 above the water level. The riser receives thedrill string and provides a conduit for return of the drilling mud.

The subsurface blowout preventer stack, indicated generally at 18, isinitially mounted on a cart or sled 20 to one side of the moon pool 14on the deck 10. The sled 20 serves as a test stump for testing of thestack before it is lowered to the template on the ocean floor. The sled20 has a pair of skids, one of which is indicated at 22, which arespaced. apart sufficiently so that the sled or cart 20 can bridge themoon pool 14, the skids 22 resting on the deck 10 on either side of themoon pool. This arrangement permits the blowout preventer stack assembly18 to be moved into position over the moon pool while it remainsanchored to the test stump.

The blowout preventer stack assembly 18 is basically of conventionalconstruction with one exception, which will be hereinafter described.Thus the blowout preventer stack assembly includes a frame consisting ofat least three vertical guide pipes 24, 26, and 28 which are equallyspaced from each other. The bottom end of the guide pipes are providedwith conical skirts 30, for guiding the pipes onto mating alignmentposts (not shown) on the base or template. Mounted within the framework,including the three guide posts, are the axially aligned blowoutpreventers indicated at 32 and 34. A conventional stab connector 36 isprovided at the lower end of the stack assembly for connecting the stackonto the well casing. A riser stab assembly 38 provides a stabconnection of the stack to a riser.

In order to provide positive guidance of the blowout preventer stackassembly 18 while lowering the stack down through the moon pool 14,there is provided a guidance assembly 40 mounted on the port side of themoon pool 14. The guidance assembly 40 includes two vertical tracks 42and 44 in the form of rods or pipes which extend parallel to each otherfrom a point substantially below the water line to a point slightlybelow the box girders 16. The lower ends of the guide rods 42 and 44 aretapered to a point.

The guide rod 42 is supported by a framework which can be assembled anddisassembled to removably support the associated guide rod to the sideof the moon pool. This framework assembly is shown schematically in FIG.3. The supporting framework includes an upper pintle 46 and a lowerpintle 48 connected to the rod 42 by an upper horizontal brace 50 andlower horizontal brace 52. The upper and lower pintles are held inspaced relationship by a vertical member 54. The upper end of the guiderod 42 is rigidly tied to the upper pintle 46 by a diagonal brace 56.

Lateral rigidity is provided by a rectangular frame assembly including apintle 58, horizontal member 60, diagonal member 62, and vertical brace64. The outer end of the horizontal member is in the form of a cleviswhich receives a bracket 66 extending from the brace 50. A removable pin68 locks the bracket 66 in the clevis of the horizontal member 60. Theupper end of the diagonal brace 62 is connected through a removablecollar 70 to the upper end of the guide rod 42. The pintles 46, 48, and58 fit into hinge brackets 72, 74, and 76, respectively, which areanchored to the sidewall of the moon pool 14. Thus the entire guideassembly 40 can be removed by lifting the pintles out of the hingebrackets 72, 74 and 76, and disassembling the assembly into two sectionswhich can be readily stowed out of the way.

Details of the guide structure are shown in FIGS. 4, 5, and 6. The rod42 is provided with a projecting or radial flange 78 which is welded tothe guide rod 42 over substantially the full length thereof. The crossmembers and braces are made from pipe sections which are welded togetherin a conventional manner, the horizontal members 50 and 52 being joinedto the flange 78 by gusset plates 80 and 82. Similarly the upper end ofthe diagonal brace 56 is connected to the flange 78 by a gusset plate84. The frame members 60, 62, and 64, as shown in FIG. 5, are made ofpipe welded together. The free end of the horizontal member 60 isslotted to form a clevis. The slot fits over the flange 66 and a pin isinserted through a hole 86.

A short section of pipe 88 is welded to the upper end of the diagonalbrace 56, as shown in FIG. 6, and is cross-braced by a bracket 90. Theouter end of the diagonal brace 62 is joined to the pipe section 88 by acollar 92 that is locked in place by pins 94 and 96 which are insertedthrough matching holes extending through the collar 92 and the ends ofthe pipe sections 62 and 88. The pins may have toggles on the ends forretaining the pins after they are inserted, or the pins may beconventional bolts.

The guide rod 44 is removably supported from the side of the moon poolby the same type-of supporting framework. Thus the guide rods 42 and 44are held in vertical parallel relationship adjacent one side of the moonpool.

As shown in FIG. 2, the blowout preventer stack 18 is positioned overthe moon pool such that the guide post 26 on the stack assembly isopposite the guide rod 42. A false post 100 is provided on the stackassembly in circumferential position to be directly opposite the guiderod 44. The posts 26 and 100 of the stack assembly 18 are linked to theguide rods 42 and 44 respectively by conical guide assemblies 102 and104, respectively.

Referring to FIGS. 7 and 8, a conical guide assembly is shown in detail.The assembly 102 includes a cylin drical sleeve 106 which is slottedalong one side, as indicated at 108. Secured to the top edge of thesleeve 106 is a conical section 110 which flares outwardly at the upperend. The conical section has a slot 112 along one side which is alignedwith the slot 108. The aligned slots 108 and 112 permit the sleeve andconical section to slide along the guide rod 40 with the supportingflange 78 extending out through the slots. A pair of parallel flatplates 1 13 and 114 project outwardly from the outside of the sleeve 106and conical section 1 10 on either side of the slots to provide guidesurfaces for the supporting flange 78. The assembly is strengthened byannular reinforcing flanges 116, 118, 120, and 122 which surround theoutside of the sleeve and conical section and are welded thereto in aunitary structure. Radial plates 124 and 126 provide additionalstiffness to the assembly.

To connect the guide assembly 102 to the stack assembly 18, the guidepost 26, which is .normally slotted along one side as indicated at 130to permit a guide cable to be inserted through the center of the guidepost 26, has a coupling framework permanently secured to the outside ofthe post. This coupling assembly, as shown in FIGS. 7 and 8, includes anannular flange 132 which surrounds the outside of the post 26 and has aradial slot 134 aligned with and matching the slot 130 in the guide post26. Above the flange 132, an elongated vertically extending T-slot isformed by a pair of flat guide plates 136 and 138 lying in a verticalplane tangential to the post 26 and being horizontally spaced from eachother so as to provide a slot 139 between the inner edges of the plates.A radial flange 140 which is welded or otherwise rigidly attached to thesleeve 106 and conical section 110 forms a T-guide with a rectangularplate 142 secured to the outer projecting edge of the radial flange 140.

The guide assembly 102 is detachably connected to the guide post 26 bysliding the assembly down the rod 42 with the radial flange 140 slippinginto the slot 139 between the plates I36 and 138 and with the guideplate 142 positioned between the guide post 26 and the plates 136 and138, as best seen in FIG. 8. The guide plate 142 is laterally restrainedby angle guide members 144 and 146 which extend vertically upward fromthe flange 132 with the outer edges being welded or otherwise attachedto the plates 136 and 138, respectively. The inner edges of the angleguides 144 and 146 form a slot 147 extending parallel to the slot 130. Aplurality of horizontal reinforcing plates 148 are axially spaced, theplates having an inner radius corresponding to the outside of the pipe26 to which the plates are welded. The plates 148 are also welded to thevertical plates 136, 138 and the angle guides 144 and 146 to provide anintegral rigid structure.

Initially the guide assemblies 102 and 104 are positioned adjacent thetop of the guide rods 42 and 44. They are each held in this position bya locking pin 150 which is inserted through diametrically aligned holes152 in the sleeve 106 when aligned with corresponding holes through therespective guide rods. This holds the guide assemblies 102 and 104 outof the way above the level of the coupling assembly on the guide post 26and 100, as shown by the phantom position of the coupling assembly 102in FIG. 1. After the sled and stack as sembly 18 are moved into positionover the moon pool, the pin 150 is removed and the guide assemblies 102and 104 are lowered into engagement with the top of the flanges 132 andthe transverse guide plates 142 positioned behind the plates 136 and138. A locking pin 154 is inserted through aligned openings 156extending through the plates 136, 142, and 144 to hold the guideassemblies in place.

Once the guide assemblies 102 and 104 are coupled respectively to thepipes 26 and 100, the stack assem bly 18 can be lifted and the sled orcart 20 withdrawn. Depending upon whether there is sufficient clearanceor not, the lifting can be done in several ways. Assuming sufficientclearance, the rotary table can be moved back in position over thesub-base of the rig with the stack still on the sled 20. A riser is thenlowered by the rig through the rotary table and stabbed into the riserconnector 38. The riser is then used to lift the stack assembly 18 offthe sled 20 by means of the derrick rig, in conventional manner. Afterthe sled 20 is removed, the riser and stack assembly are lowered as aunit by the rig down through the moon pool 14 to the template on theocean floor. The coupling assemblies 102 and 104 provide positiveguidance of the stack assembly along the length of the guide rods 42 and44 until the stack assembly is substantially immersed in the water andthe coupling assemblies slide off the lower end of the guide rods. Whenso immersed, swinging of the stack assembly is sufficiently damped bythe water to prevent any substantial swinging of the stack from side toside as it is lowered on down through the bottom of the ship. When theblowout preventer stack is retrieved after completion of the drillingoperation, the conical sections 110 of the coupling assemblies 102 and104 provide guidance for re-engaging the guide assemblies with thetapered lower ends of the guide rods 40 and 42.

If there is not sufficient clearance for the stack assembly to permitthe rotary table to be moved into position over the stack, a harness maybe rigged from the box beams 16 and extending below the sled. Thetraveling block of the rig is then used to lift the stack assembly offthe sled 20. The sled is then withdrawn and the stack assembly lowereddown into the harness. The r0- tary table can then be moved intoposition over the stack; the riser is then lowered through the rotarytable and stabbed into the riser connector 38. In any case, it will beseen that the stack assembly is prevented from moving laterally at alltimes by the guide assembly.

Referring to FIGS. 9-14, an alternative guide structure, particularlyadapted for a semisubmersible type drilling platform, is shown. Theconventional semisubmersible drilling platform includes a main deck 200which is supported on a plurality of columns (not shown) which inturn-extend below the ocean surface to submerged hulls that give buoyantsupport. The main deck 200 is provided with a drilling opening 202. Themain deck may be held high above the level of the water to permit highwaves to pass beneath the structure. A vertical guidance assembly forguiding the stack assembly while it is being lowered through thedrilling opening and into the water includes a girder structureextending down from the underside of the main deck 200 to a pointslightly above the normal water level. This structure includes a pair ofvertical parallel I- beams 204 and 206. The lower ends of the I-beamsare joined to diagonal braces 208 and 210 by gussett plates 212. Theupper ends of the diagonal braces 208 and 210 are anchored to theunderside of the main deck 200 by suitable anchoring plates 214. Theupper ends of the I-beams 204 and 206 extend past one edge of theopening 202 and terminates well above the level of the main deck 200adjacent one side of the drilling opening 202. Diagonal braces 216 and217 extend from the upper ends down to the deck 200. The I-beams 204 and206 are made more rigid by means of horizontal and diagonal crossbracing between the Ibeams 204 and 206 and the diagonal members 208 and210 to form rigid trusses.

The upper ends of the I-beams 204 and 206 are connected by a horizontaltop beam 218 which projects horizontally beyond the I'beams at eitherend. Lateral rigidity is provided for the I-beams 204 and 206 bydiagonal braces 220 and 222 which are joined at their lower ends to thedeck 200 and at their upper ends to the I-beams 204 and 206.

The vertical beams 204 and 206 support vertical tracks or guides 224 and226 which are in the form of semi-circular channels which extend fromthe level of the deck 200 down to the lower end of the supportingI-beams. Stiffening flanges 228 and 230 run the length of the guides onthe outside of the channels. Integral supporting brackets 231 are spacedalong the length of the tracks for securing the tracks to the supportingframework. Each bracket includes a horizontal plate 232 and a backingplate 234. The backing plates are bolted or otherwise secured torespective horizontal cross-brace members 236. The lower ends of thetracks 224 and 226 terminate in flared or bell-mouth sections 238 and239 for guiding the blowout preventer stack frame on and off the lowerend of the tracks.

As shown in FIG. 9., the blowout preventer stack includes four guideposts 240, 242, 244, and 246. A guide framework is added to the blowoutstack assembly which includes a pair of spaced parallel guide rods 248and 250. The guide rods 248 and 250 are rigidly supported from the guideposts 240 and 242 by a suitable tubular framework, indicated generallyat 252, which includes horizontal tubes 254 extending between andsecured to the guide rods 248 and 250 and connector tubes 256 and 258which extend between the guide post 248 and 250 and the horizontal tubes254. Suitable cross bracing tubes, such as 260 and 262, provide rigidityto the guide framework 252.

As in the embodiment described above in connection with FIGS. 1-8, theblowout preventer stack assembly is normally stored on a test stump inthe form of a sled or cart which is suffieiently large to span thedrilling opening 202. Thus the cart can be used to move the blowoutpreventer stack assembly into position over the drilling hole with therods 250 and 248 aligned with the lower guide tracks 224 and 226. Tolock the blowout preventer stack assembly in proper position forlowering the assembly through the drilling opening 202, a pair of upperguide track guide sections 264 and 268 are arranged to be moved apartout of alignment with the lower guides 224 and 226. To this end, theupper end of the guide section 264 includes a bracket assembly 270 whichis pivotally connected to the cross member 218 by a hinge bolt 272.Similarly the upper end of the guide section 268 has a bracket 274 whichis pivotally supported from the cross member 218 by a hinge bolt 276. Asbest seen in FIG. 10, with the bolt 272 as the pivot axis, the upperguide section 264 can be swung to one side where it can be held by alocking pin 278 which extends through a bracket 280 secured to the lowerend of the guide section 264 and a hole in plate 282 secured to thediagonal brace 222. The upper end of the guide section 264 has the outerhalf of the channel removed along a diagonal line 284 so that when theguide section 264 is pivoted off to one side, there is clearance for theguide rod 248 to move into position against the back of the channel. Theupper end of the upper guide 268 is similarly relieved along a diagonal286.

Once the guide rods 248 and 250 are moved into position so as to bealigned with the lower guides 248 and 250, the upper guides 264 and 268are swung into a vertical position in which the channels fit around theguide rods 248 and 250. In this position, the locking pin 278 isinserted through an aligned hole in a cross member 288. Sirriilarly apin 290 is used to lock the lower end of the guide section 268 in itsoperative vertical position to the cross member 288 or to the openposition to a plate 292 on the diagonal brace 220.

What is claimed is:

1. Apparatus for guiding a blowout preventer assem bly and the likealong a predetermined path during movement of the assembly to and froman off-shore drilling installation out of and into water over a wellhead, the apparatus comprising: guide means rigidly securable to thedrilling installation defining a pair of spaced vertical tracks disposedparallel to and to one side of the predetermined path so as not to limitthe horizontal dimension of a blowout preventer assembly being handled,the tracks having lower ends disposed so that when a blowout preventerassembly engages or disengages the tracks the assembly is substantiallyimmersed in water, the tracks having upper ends above the location inthe installation at which the blowout preventer assembly is stored,guide elements engageable with the tracks and secured to the blowoutpreventer assembly for movement therewith along the path out of and intoengagement with the lower ends of the tracks, the guide elements beingcooperatively configured in association with the tracks for locking theguide elements to the tracks to restrict motion of the guide elements tomovement lengthwise of the tracks when engaged therewith, and means forcoupling and decoupling the blowout preventer assembly via the guideelements to the tracks at a location between the upper and lower ends ofthe tracks substantially adja cent the storage location of the assembly.

2. In an off-shore floating drilling vessel subject to heave, roll, andpitch, apparatus for guiding equipment while lowering the equipment fromthe top of the vessel through an opening into the water comprising:track means including a pair of parallel tracks vertically mounted tothe vessel and extending from above the opening down through theopening, the tracks being rod-shaped with a supporting flange extendinglengthwise of the track for supporting the track from the vessel, guidemeans engaging the tracks and movable therealong, and means coupling theguide means to said equipment, the guide means moving with the equipmentas it is lowered through the opening to guide the equipment along thetracks into the water, the guide means disengaging from the tracks asthe equipment enters the water, the guide means including sleeves havinga slot, the sleeves slidably engaging the respective tracks with theflanges extending through the slots.

3. Apparatus of claim 2 wherein the coupling means includes means fordetachably connecting the sleeves of the guide means to the equipment.

4. Apparatus of claim 3 wherein the means for detachably coupling therespective sleeves to the equipment includes means forming a T -slotextending vertically of the equipment, and T-shaped members projectingfrom each sleeve adapted to slide into the T-shaped slot by sliding theassociated sleeve along the track, and means for locking the T-shapedmember in the mating slot.

5. In an off-shore floating drilling vessel subject to heave, roll, andpitch, apparatus for guiding the equipment while lowering the equipmentfrom the top of the vessel through an opening into the water comprising:track means including a pair of parallel tracks vertically mounted tothe vessel and extending from above the opening down through theopening, guide means engaging the traeks and movable therealong, meanscoupling the guide means to said equipment, the guide means moving withthe equipment as it is lowered through the opening to guide theequipment along the tracks into the water, the tracks beingchannelshaped, the guide means including means slidably engaging thechannels, the channels opening in opposite directions relative to eachother to retain the guide means in the channels.

6. Apparatus of claim 5 wherein a portion of at least one of the trackchannels adjacent the upper end is movable in the direction toward andaway from the open side of the channel to permit the guide means to bepositioned within the channels.

7. Apparatus for guiding a blowout preventer assembly and the like alonga predetermined path during movement of the assembly to and from anoff-shore drilling installation out of and into water over a wellhead,the apparatus comprising: guide means rigidly securable to the drillinginstallation defining a pair of spaced tracks disposed parallel to thepredetermined path, the tracks having lower ends disposed proximate thewater surface below the location in the installation at which a blowoutpreventer assembly is stored, the tracks having upper ends above saidassembly storage location, guide elements securable to a blowoutpreventer assembly as a part of the structure thereof for movement withthe assembly to and from the wellhead and engageable with the tracks,the guide elements being cooperatively configured in association withthe tracks for substantially only sliding motion along the tracks whenengaged therewith, and means for coupling and decoupling a blowoutpreventer assembly via the guide elements to the tracks at a location onthe tracks between the ends thereof.

8. A method of transferring a blowout preventer stack, having securedthereto an outer frame with vertical guide members, from the deck of adrilling vessel into the water by a drilling rig positioned over adrilling opening in the deck, comprising the steps of: mounting thestack on a movable frame for storage on the deck, moving the frame overthe opening, coupling the stack frame guide members to vertical guideslocated only on one side of the opening while supporting the stack onthe movable frame, lifting the stack along the vertical guides off themovable frame, removing the movable frame, and lowering the stack intothe water along the vertical guides.

9. A method of lowering a blowout preventer stack having secured theretoan outer frame with vertical guide members from the deck of a drillingvessel through a drilling opening in the deck below a drilling rig,comprising the steps of: mounting the stack on a test frame supported onthe deck, moving the test frame over the opening, securing the verticalguide members to vertical tracks extending above and below the deckwithout vertical movement of the stack from the frame, lifting the stackalong the tracks off the test frame, removing the test frame, andlowering the stack and the guide members therewith along the tracks intothe water.

10. In an off-shore floating drilling vessel subject to heave, roll, andpitch, apparatus for guiding the equipment while lowering the equipmentfrom the top of the vessel through an opening into the water comprising:track means including a pair of parallel tracks vertically mounted tothe vessel and extending from above the opening down through theopening, guide means en gaging the tracks and movable therealong, meanscoupling the guide means to said equipment, the guide means moving withthe equipment as it is lowered through the opening to guide theequipment along the tracks into the water, the guide means disengagingfrom the tracks as the equipment enters the water, the track meansincluding a framework attached to each track, and means detachablyconnecting the framework to the vessel to permit the tracks to beremoved from the structure of the vessel around the opening

1. Apparatus for guiding a blowout preventer assembly and the like alonga predetermined path during movement of the assembly to and from anoff-shore drilling installation out of and into water over a wellhead,the apparatus comprising: guide means rigidly securable to the drillinginstallation defining a pair of spaced vertical tracks disposed parallelto and to one side of the predetermined path so as not to limit thehorizontal dimension of a blowout preventer assembly being handled, thetracks having lower ends disposed so that when a blowout preventerassembly engages or disengages the tracks the assembly is substantiallyimmersed in water, the tracks having upper ends above the location inthe installation at which the blowout preventer assembly is stored,guide elements engageable with the tracks and secured to the blowoutpreventer assembly for movement therewith along the path out of and intoengagement with the lower ends of the tracks, the guide elements beingcooperatively configured in association with the tracks for locking theguide elements to the tracks to restrict motion of the guide elements tomovement lengthwise of the tracks when engaged therewith, and means forcoupling and decoupling the blowout preventer assembly via the guideelements to the tracks at a location between the upper and lower ends ofthe tracks substantially adjacent the storage location of the assembly.2. In an off-shore floating drilling vessel subject to heave, roll, andpitch, apparatus for guiding equipment while lowering the equipment fromthe top of the vessel through an opening into the water comprising:track means including a pair of parallel tracks vertically mounted tothe vessel and extending from above the opening down through theopening, the tracks being rod-shaped with a supporting flange extendinglengthwise of the track for supporting the track from the vessel, guidemeans engaging the tracks and movable therealong, and means coupling theguide means to said equipment, the guide means moving with the equipmentas it is lowered through the opening to guide the equipment along thetracks into the water, the guide means disengaging from the tracks asthe equipment enters the water, the guide means including sleeves havinga slot, the sleeves slidably engaging the respective tracks with theflanges extending through the slots.
 3. Apparatus of claim 2 wherein thecoupling means includes means for detachably connecting the sleeves ofthe guide means to the equipment.
 4. Apparatus of claim 3 wherein themeans for detachably coupling the respective sleeves to the equipmentincludes means forming a T-slot extending vertically of the equipment,and T-shaped members projecting from each sleeve adapted to slide intothe T-shaped slot by sliding the associated sleeve along the track, andmeans for locking the T-shaped member in the mating slot.
 5. In anoff-shore floating drilling vessel subject to heave, roll, and pitch,apparatus for guiding the equipment while lowering the equipment fromthe top of the vessel through an opening into the water comprising:track means including a pair of parallel tracks vertically mounted tothe vessel and extending from above the opening down through theopening, guide means engaging the tracks and movable therealong, meanscoupling the guide means to said equipment, the guide means moving withthe equipment as it is lowered through the opening to guide theequipment along the tracks into the water, the tracks beingchannelshaped, the guide means including means slidably engaging thechannels, the channels opening in opposite directions relative to eachother to retain the guide means in the channels.
 6. Apparatus of claim 5wherein a portion of at least one of the track channels adjacent theupper end is movable in the direction toward and away from the open sideof the channel to permit the guide means to be positioned within thechannels.
 7. Apparatus for guiding a blowout preventer assembly and thelike along a predetermined path during movement of the assembly to andfrom an off-shore drilling installation out of and into water over awellhead, the apparatus comprising: guide means rigidly securable to thedrilling installation defining a pair of spaced tracks disposed parallelto the predetermined path, the tracks having lower ends disposedproximate the water surface below the location in the installation atwhich a blowout preventer assembly is stored, the tracks having upperends above said assembly storage location, guide elements securable to ablowout preventer assembly as a part of the structure thereof formovement with the assembly to and from the wellhead and engageable withthe tracks, the guide elements being cooperatively configured inassociation with the tracks for substantially only sliding motion alongthe tracks when engaged therewith, and means for coupling and decouplinga blowout preventer assembly via the guide elements to the tracks at alocation on the tracks between the ends thereof.
 8. A method oftransferring a blowout preventer stack, having secured thereto an outerframe with vertical guide members, from the deck of a drilling vesselinto the water by a drilling rig positioned over a drilling opening inthe deck, comprising the steps of: mounting the stack on a movable framefor storage on the deck, moving the frame over the opening, coupling thestack frame guide members to vertical guides located only on one side ofthe opening while supporting the stack on the movable frame, lifting thestack along the vertical guides off the movable frame, removing themovable frame, and lowering the stack into the water along the verticalguides.
 9. A method of lowering a blowout preventer stack having securedthereto an outer frame with vertical guide members from the deck of adrilling vessel through a drilling opening in the deck below a drillingrig, comprising the steps of: mounting the stack on a test framesupported on the deck, moving the test frame over the opening, securingthe vertical guide members to vertical tracks extending above and belowthe deck without vertical movement of the stack from the frame, liftingthe stack along the tracks off the test frame, removing the test frame,and lowering the stack and the guide members therewith along the tracksinto the water.
 10. In an off-shore floating drilling vessel subject toheave, roll, and pitch, apparatus for guiding the equipment whilelowering the equipment from the top of the vessel through an openinginto the water comprising: track means including a pair of paralleltracks vertically mounted to the vessel and extending from above theopening down through the opening, guide means engaging the tracks andmovable therealong, means coupling the guide means to said equipment,the guide means moving with the equipment as it is lowered through theopening to guide the equipment along the tracks into the water, theguide means disengaging from the tracks as the equipment enters thewater, the track means including a framework attached to each track, andmeans detachably connecting the framework to the vessel to permit thetracks to be removed from the structure of the vessel around the openingwhen not in use.